The present invention relates generally to fluid control devices, and more particularly, to a device which controls the rate of fluid flow through a conduit.
Fluid administration systems are widely used in the medical field for providing parenteral fluids to a patient. Such systems normally include a manual flow control device, such as a roller clamp, for controlling the flow of fluid through the administration set conduit. These roller clamps are typically located upstream from the section of the conduit operated on by the pumping system. Because they are separate from the pumping system, manual action is needed to configure them properly for pumping action or for removing the conduit from the pump. For example, once the conduit is inserted in the pump, the flow stop must be configured to the full flow position so that the pump can control the flow through the conduit. When removing the conduit from the pump, the flow controller must first be set in the flow stop position.
One conventional flow control device includes a ribbed roller having ends which travel within laterally spaced apart furrows formed in vertical sidewalls of a housing through which flexible round tubing of the pumping system passes. The housing also includes an opposing wall that is inclined at an angle to the path of the roller. The housing receives the round tubing between the path of the roller and the opposing wall. By varying the position of the roller along the furrows, the degree of tubing closure and hence the flow rate through the system, can be controlled.
Flow control devices of this type, however, are limited in that the flexible tubing can become flattened or otherwise dimensionally deformed as a result of the compression force exerted by the clamp, lever, or roller. This deformation may progress with time, with the result that the flow rate in the system changes from an expected rate.
Other fluid control devices embody a flexible round conduit that connects with and replaces a segment of conventional tubing and includes a cylindrical insert member disposed within the conduit. The cylindrical insert defines a channel for fluid flow, a portion of which has a progressively increasing cross-sectional area along its axis. An outer sleeve fits over the flexible cylindrical conduit and embodies a roller that slides within a track formed in the outer sleeve. By positioning the roller along the flexible cylindrical conduit, portions of the flexible conduit are forced into the channel defined by the cylindrical insert, thereby controlling fluid flow. This device, however, is limited since the cross-sectional area of the cylindrical conduit may change with time and therefore, require the user to make adjustments to achieve desired flow rates. Moreover, the device is limited since it embodies a relatively complex design having a number of interacting and moving parts that require high precision manufacturing.
While it would be desirable to provide a flow control device that can be operated automatically by a pump, such a flow control device should also be operable manually so that certain procedures, such as priming, can be carried out. Additionally, such a flow control device should have a complete flow stop portion and a full flow portion. It would also be desirable to provide an integrated flow control in a pumping segment operable automatically by the pump wherein the flow controller has greater accuracy and is less susceptible to deforming over time.
Accordingly, a need exists for a new and improved flow control device for fluid administration systems that can be operated automatically by a pump but which can also be operated manually and which provides a full range of flow control more accurately and with a reduced liklihood of deforming with use. The invention fulfills these needs.